Since I have been spending a lot of time researching how to effectively breakout and route large BGAs, my initial posts will be related to designing with BGAs; however, in addition to that topic, I am interested in interactive and automatic routing. BGAs that are difficult to route are either very large (over 1500 pins) or with a very small pitch (less than .8mm). In both cases the most common reason for routing trouble is the requirement to use only through vias. We are fortunate that the handheld electronics industry has embraced HDI almost entirely, yet in most other segments use of through-hole vias still dominate. Using micro-vias in an HDI stackup enables more effective routing resulting in fewer layers and less time to completion.
If you are struggling to complete a through-hole design because the BGAs are too difficult to route or require too many layers, why haven’t you started using HDI? My interest in this blog is to find the tipping point at which going to HDI will allow you to succeed with either very large pin-count or very small pin-pitch BGAs. If BGAs caused your company to start using HDI, what specifically was your tipping point? If your company is not moving towards HDI, at what point will you be unable to complete a design with these BGAs?